[libvirt] [FOR 1.3.0 PATCH] conf: add net device prefix for Xen
Daniel P. Berrange
berrange at redhat.com
Mon Dec 7 18:52:12 UTC 2015
On Mon, Dec 07, 2015 at 09:42:21AM -0700, Jim Fehlig wrote:
> In commit d2e5538b1, the libxl driver was changed to copy interface
> names autogenerated by libxl to the corresponding network def in the
> domain's virDomainDef object. The copied name is freed when the domain
> transitions to the shutoff state. But when migrating a domain, the
> autogenerated name is included in the XML sent to the destination host.
> It is possible an interface with the same name already exists on the
> destination host, causing migration to fail. Indeed the Xen project's
> OSSTEST CI already encountered such a failure.
>
> This patch defines another VIR_NET_GENERATED_PREFIX for Xen, allowing
> the autogenerated names to be excluded when parsing and formatting
> inactive config.
>
> Signed-off-by: Jim Fehlig <jfehlig at suse.com>
> ---
>
> This is an alternative approach to Joao's fix for this regression
>
> https://www.redhat.com/archives/libvir-list/2015-December/msg00197.html
>
> I think it is the same approach used by the qemu driver. My only
> reservation is that it expands the potential for clashes with
> user-defined names. I.e. with this change both 'vnet' and 'vif' are
> reserved prefixes.
Hmm, yes, tricky one.
If we only care about XML parsing, then you could register a post
parse callback instead to do this.
I'm not clear why we also have it in the virDomainNetDefFormat
method - and we can't solve that with a post-parse callback.
The other option would be to make the reserved prefix be a
capability that the parser/formatter could read.
>
> src/conf/domain_conf.c | 6 ++++--
> src/conf/domain_conf.h | 4 ++++
> src/libxl/libxl_domain.c | 5 +++--
> 3 files changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
> index 2f5c0ed..debcf4e 100644
> --- a/src/conf/domain_conf.c
> +++ b/src/conf/domain_conf.c
> @@ -8428,7 +8428,8 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt,
> ifname = virXMLPropString(cur, "dev");
> if (ifname &&
> (flags & VIR_DOMAIN_DEF_PARSE_INACTIVE) &&
> - STRPREFIX(ifname, VIR_NET_GENERATED_PREFIX)) {
> + (STRPREFIX(ifname, VIR_NET_GENERATED_PREFIX) ||
> + STRPREFIX(ifname, VIR_NET_GENERATED_PREFIX_XEN))) {
> /* An auto-generated target name, blank it out */
> VIR_FREE(ifname);
> }
> @@ -19790,7 +19791,8 @@ virDomainNetDefFormat(virBufferPtr buf,
> virBufferEscapeString(buf, "<backenddomain name='%s'/>\n", def->domain_name);
> if (def->ifname &&
> !((flags & VIR_DOMAIN_DEF_FORMAT_INACTIVE) &&
> - (STRPREFIX(def->ifname, VIR_NET_GENERATED_PREFIX)))) {
> + (STRPREFIX(def->ifname, VIR_NET_GENERATED_PREFIX) ||
> + STRPREFIX(def->ifname, VIR_NET_GENERATED_PREFIX_XEN)))) {
> /* Skip auto-generated target names for inactive config. */
> virBufferEscapeString(buf, "<target dev='%s'/>\n", def->ifname);
> }
> diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
> index 90d8e13..d2cc26f 100644
> --- a/src/conf/domain_conf.h
> +++ b/src/conf/domain_conf.h
> @@ -1085,6 +1085,10 @@ struct _virDomainNetDef {
> * by libvirt, and cannot be used for a persistent network name. */
> # define VIR_NET_GENERATED_PREFIX "vnet"
>
> +/* Used for prefix of ifname of any network name generated dynamically
> + * by libvirt for Xen, and cannot be used for a persistent network name. */
> +# define VIR_NET_GENERATED_PREFIX_XEN "vif"
> +
> typedef enum {
> VIR_DOMAIN_CHR_DEVICE_STATE_DEFAULT = 0,
> VIR_DOMAIN_CHR_DEVICE_STATE_CONNECTED,
> diff --git a/src/libxl/libxl_domain.c b/src/libxl/libxl_domain.c
> index ef92974..c5d84a4 100644
> --- a/src/libxl/libxl_domain.c
> +++ b/src/libxl/libxl_domain.c
> @@ -734,7 +734,7 @@ libxlDomainCleanup(libxlDriverPrivatePtr driver,
> for (i = 0; i < vm->def->nnets; i++) {
> virDomainNetDefPtr net = vm->def->nets[i];
>
> - if (STRPREFIX(net->ifname, "vif"))
> + if (STRPREFIX(net->ifname, VIR_NET_GENERATED_PREFIX_XEN))
> VIR_FREE(net->ifname);
> }
> }
> @@ -918,7 +918,8 @@ libxlDomainCreateIfaceNames(virDomainDefPtr def, libxl_domain_config *d_config)
> if (net->ifname)
> continue;
>
> - ignore_value(virAsprintf(&net->ifname, "vif%d.%d%s",
> + ignore_value(virAsprintf(&net->ifname,
> + VIR_NET_GENERATED_PREFIX_XEN "%d.%d%s",
> def->id, x_nic->devid, suffix));
> }
> }
> --
> 2.6.1
>
> --
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> libvir-list at redhat.com
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Regards,
Daniel
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